Creepage protection device can prevent personal electric shock and fire accident effectively. Especially GFCI, with function of creepage protection and neutral grounding protection, has been used widely.
Creepage protection device may also have fault emerged in itself, such as life termination of the inside component, causing the creepage protection function to be lost, and in this instance, if we use this device unceasingly, a life threatening electric shock or fire accident may be present.
Thus, some GFCI manufacturers start to design control circuit of the GFCI which has self-diagnosis function, accordingly to diagnose the creepage protection device of the control circuit if in good condition even having function of creepage protection, such as described in U.S. Pat. No. 6,952,150 a self-diagnosis circuit for indicating the end of life of an interrupter. However, for the self-diagnosis circuit is coupled in a test circuit, requiring manpower-provided simulated signal, but having no capability of self-diagnosis, the self-diagnosis circuit can not duly reflect the stand or fall instance of the circuit interrupter in the operation, without deep-dyed self-diagnosis function.
Besides, due to the self-diagnosis circuit may have fault emerged in itself, such as life termination of the inside component, causing self-diagnosis function to be lost, in this instance, the self-diagnosis circuit may still displays in situation of creepage protection although creepage protection function has already been lost. If we use this device unceasingly, a life threatening electric shock or fire accident may be present.